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  • 1
    Electronic Resource
    Electronic Resource
    Histochemical and cytochemical demonstration of Ca++-ATPase activity in the stellate cells of the adenohypophysis of the guinea pig (1985)
    Springer
    Histochemistry and cell biology 83 (1985), S. 195-200 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The histo- and cytochemical localization of Ca++-ATPase activity in the adenohypophysis of the guinea pig was studied utilizing a newly developed method (Ando et al. 1981). An intense reaction was observed in the wall of the blood vessels and between non-secretory cells (stellate cells) and endocrine cells of the pars distalis. Under the electron microscope the Ca++-ATPase reaction product was located extracellularly in relation to the plasmalemma of the stellate cells. This reaction was dependent on Ca++ and the substrate, ATP, and reduced by the addition of 0,1 mM quercetin to the standard incubation medium. Preheating of the sections before incubation completely inhibited the enzyme activity. When Mg++ in different concentrations were substituted for Ca++ in the incubation medium the reaction was always reduced. Both Ca++ and Mg++ in the incubation medium also reduced the reaction. The plasmalemma of the endocrine cells contains no demonstrable amount of Ca++-ATPase activity. The function of the Ca++-ATPase activity is discussed in relation to the regulation of the extracellular Ca++ concentration which seems to be important with respect not only to the secretory process of the endocrine cells but also to the metabolism of the adenohypophysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00953983
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  • 2
    Electronic Resource
    Electronic Resource
    A new histo-and cytochemical method for demonstration of cyclic 3′, 5′-nucleotide phosphodiesterase activity in retinal rod photoreceptor cells of the rat (1984)
    Springer
    Histochemistry and cell biology 81 (1984), S. 445-451 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cyclic 3′, 5′-mononucleotide phosphodiesterase (cyclic nucleotide PDEase) activity was studied histo-and cytochemically in the retinal rod photoreceptor cells of the rat by means of a newly developed technique utilizing the intrinsic 5′ nucleotidase activity instead of an exogenous 5′ nucleotidase source (snake venom). Cyclic GMP and cyclic AMP were used as substrates. When cyclic GMP was used as a substrate, the intense activity of phosphodiesterase (PDEase) was distributed over the entire rod outer segments; reaction product was observed on the plasmalemma and on the disk membranes of the outer segments. A slight reaction was also observed on the plasmalemma of the inner segments. However, no precipitate was found in the perinuclear and synaptic regions of the rod photoreceptors. In contrast, when cyclic AMP was utilized as a substrate, a moderate reaction was seen in the synaptic region of the plexiform layer. The intensity of the reaction in the outer segments was much reduced in comparison to the results with cyclic GMP. The enzyme activity was almost completely inhibited by 2 mM 3-isobutyl-1-methylxanthine (IBMX) or 2 mM theophylline, which were potent inhibitors of PDEase. To confirm the propriety of our new cytochemical method, the localization of 5′ nucleotidase was also studied utilizing 5′ AMP or 5′ GMP as substrates. In contrast to the activity of cyclic nucleotide PDEase, the activity of 5′ nucleotidase was distributed on all membranes of the photoreceptors from the synaptic outer plexiform layer to the tip of outer segments. After inhibition of the intrinsic 5′ nucleotidase activity with the use of 1 mM Ni-ions or 10 mM NaF no demonstration of cyclic nucleotide PDEase activity was possible; the existence of intrinsic 5′ nucleotidase activity is necessary for the release of free phosphateions from 5′ AMP (5′ GMP), which are a prerequisite for the histochemical reaction. For comparison, some sections were incubated with the conventional cyclic nucleotide PDEase incubation medium containing snake venom from Ophiophagus hannah. With this conventional method, morphological preservation was extremely poor, and moreover, the reaction itself was weaker than that with the presently described method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00489748
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  • 3
    Electronic Resource
    Electronic Resource
    Fluoreszenzmikroskopischer Nachweis biogener Monoamine in der Epiphysis cerebri von Rana esculenta und Rana pipiens (1970)
    Springer
    Cell & tissue research 111 (1970), S. 550-558 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ (epiphysis cerebri) ; Anura ; 5-hydroxytryptamine ; Adrenergic nerve fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Epiphysis cerebri von Rana pipiens und Rana esculenta wurde fluoreszenzmikroskopisch auf das Vorhandensein bestimmter biogener Amine untersucht. Unter normalen Bedingungen lassen sich im Parenchym der Froschepiphyse keine Amine fluoreszenzmikroskopisch darstellen. Nach Vorbehandlung der Tiere mit dem Monoaminoxydase-Hemmer Nialamid ist aber eine intensive, durch Formaldehyd-Behandlung induzierte Gelbfluoreszenz in den Sinnes- und Stützzellen zu beobachten. Mikrospektrofluorometrische Messungen zeigen, daß das Fluorophor mit 5-Hydroxytryptamin identisch ist, obwohl das Vorkommen von anderen verwandten Indolen — z.B. 5-Hydroxytryptophan und Melatonin — nicht ausgeschlossen werden kann. Grünfluoreszierende adrenerge Nervenfasern sind im meningealen Hüllbindegewebe der Epiphyse zu erkennen; einige dieser Fasern scheinen auch in die Epiphyse einzudringen. Der Nachweis von 5-Hydroxytryptamin wird im Zusammenhang mit der Frage einer Melatoninsynthese diskutiert. Das 5-Hydroxytryptamin könnte außerdem in einer funktionellen Beziehung zu einem bisher noch unbekannten Protein- der Polypeptid-Hormon des Epiphysenparenchyms stehen.
    Notes: Summary The pineal organ of Rana pipiens and Rana esculenta was studied by fluorescence microscopy for the histochemical demonstration of certain biogenic monoamines. Under normal conditions, no fluorogenic amines were visible in the organ. After pretreatment of the animal with a monoamine-oxidase inhibitor, nialamide, an intense yellow formaldehyde-induced fluorescence appeared both in the sensory cells and in the supporting cells. Microspectrofluorometric analysis indicated that the fluorophore is identical with 5-hydroxytryptamine; the presence of other closely related indoles, such as 5-hydroxytryptophan and melatonin, however, cannot be excluded. Fluorescent adrenergic nerves were found in the connective tissues surrounding the pineal organ; fluorescent fibers were observed also in the pineal parenchyma. The presence of 5-hydroxytryptamine in the anuran pineal organ is discussed with regard to the role that the amine plays in melatonin synthesis and with regard to a possible functional relation to some as yet unidentified protein- or polypeptid-hormone within the pineal parenchyma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330931
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  • 4
    Electronic Resource
    Electronic Resource
    Fluoreszenzmikroskopische und elektronenmikroskopische Untersuchungen am Pinealorgan verschiedener Vogelarten (1973)
    Springer
    Cell & tissue research 137 (1973), S. 37-62 
    Details
    ISSN: 1432-0878
    Keywords: Avian pineal organ ; 5-HT ; Adrenergic innervation ; Light-dependent functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Mit der Fluoreszenzmethode von Falck-Hillarp lassen sich Artunterschiede im Innervationsmodus der Vogelepiphyse nachweisen. Bei Passer domesticus, Carduelis chloris, Pica pica, Corvus frugilegus und Gallus domesticus treten fluoreszierende adrenerge Nervenfasern nur perivaskulär, bei Anas platyrhynchos und Excalfactoria chinensis sowohl perivaskulär als auch im Parenchym, bei Columba livia lediglich vereinzelt im Parenchym auf. Die Fluoreszenzintensität des Epiphysenparenchyms von Passer domesticus und Columba livia, die nach mikrospektrographischen Messungen auf Serotonin beruht, schwankt stark von Fanggruppe zu Fanggruppe; die großen Unterschiede sind durch tagesrhythmische Schwankungen allein nicht erklärbar. In permanenter Dunkelheit nimmt die Serotoninfluoreszenz der Taubenepiphyse beträchtlich zu. Serotonin wird auch von den aminergen Nervenfasern der Vogelepiphyse gespeichert; seine Abgabe in die Blutbahn und deren physiologische Bedeutung werden diskutiert. Die in das Lumen der Vogelepiphyse hineinragenden, von modifizierten Zilien der Pinealozyten ausgehenden Membranwirbel zeigen mit der Osmierung nach Eakin, Brandenburger, Kopsch, Kolatschev gleichartige Partikel (Durchmesser 50 Å) wie die regulär gebauten Außenglieder der retinalen und pinealen Photorezeptoren. Diese Befunde werden mit elektrophysiologischen, biochemischen und verhaltensphysiologischen Ergebnissen verglichen.
    Notes: Summary The adrenergic innervation and the parenchymal 5-HT in the pineal organ of different avian species were investigated with the method of Falck-Hillarp. The fluorophores were identified microspectrographically. An entirely perivascular localization of adrenergic nerve fibres was observed in the pineal organs of Passer domesticus, Carduelis chloris, Pica pica, Corvus frugilegus and Gallus domesticus. The pineal organs of Anas platyrhynchos and Excalfactoria chinensis showed both perivascular and parenchymal innervation. Perivascular fibres were absent from the pineal organ of Columba livia, and only a few fine fluorescent fibres appeared in its parenchyma after pretreatment with l-dopa. The intensity of the 5-HT fluorescence of the parenchyma cells showed a high individual variability. These differences apparently do not reflect a circadian 5-HT-rhythm. Continuous darkness increased the intensity of the 5-HT-fluorescence in the pineal organ of Columba livia. 5-HT was also demonstrated within the perivascular autonomic nerve fibres of the avian pineal organ. It is probable that 5-HT is released from the pineal parenchyma into the circulation. After prolonged osmium tetroxide treatment according to Eakin, Brandenburger, Kopsch, Kolatschev, the membrane whorls that are formed by the cilia of avian pinealocytes showed osmiophilic particles 50 Å in diameter. Similar particles have been observed in the regular outer segments of retinal and pineal photoreceptor cells of lower vertebrates. The above morphological results are discussed in view of electrophysiological, biochemical and behavioural observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307048
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  • 5
    Electronic Resource
    Electronic Resource
    Strukturbesonderheiten der Anurenepiphyse nach prolongierter Osmierung und Anwendung der Acetylcholinesterase-Reaktion (1971)
    Springer
    Cell & tissue research 112 (1971), S. 526-541 
    Details
    ISSN: 1432-0878
    Keywords: Anura ; Pineal organ (epiphysis) ; Prolonged osmium tetroxide fixation ; Specific sensory cell and supportive cell structures ; Acetylcholinesterase reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Mit der prolongierten Osmierung nach Friend wird an den Außengliedern der pinealen Sinneszellen von Rana temporaria eine körnige Schwärzung erzielt. Diese Partikel haben einen Durchmesser von etwa 50 Å. In Analogie zu den Befunden an den retinalen Stäbchen (Eakin und Brandenburger) wird das geschwärzte Material als das Reaktionsprodukt eines Photopigments gedeutet. Weiterhin kann man mit dieser Methode in den pinealen Stützzellen 300–2500 Å große Granula darstellen, die im Golgi-Apparat entstehen. Die für Stützzellen charakteristischen Granula ermöglichen eine sichere Erkennung kleiner Stützzellanschnitte. Obwohl der Chemismus der Friendschen Reaktion nicht bekannt ist, bewährt sich diese Fixierungsmethode bei der elektiven Darstellung bestimmter Zellstrukturen. So war es möglich, den Degenerationsablauf an den Sinneszellaußengliedern und das Verhalten von Zellfortsätzen im perivaskulären Raum präziser als bisher zu untersuchen. Mit der Acetylcholinesterase-Reaktion können in der Anurenepiphyse nur Ganglienzellen und deren Neuriten elektiv hervorgehoben werden; basaler Rezeptorenfuß und die plexiformen Zonen sind dagegen negativ.
    Notes: Summary 50 Å particles are selectively demonstrated in the cytoplasmic lamellae of the outer segments of the pineal sensory cells inRana temporaria after prolonged osmium tetroxide fixation according to Friend. In analogy to the interpretations of Eakin and Brandenburger concerning the rods of the lateral eye, it is assumed that a photopigment is present in the outer segment of the anuran pineal receptors. Furthermore, 300–2500 Å granules are demonstrated in the supportive cells; these originate in the Golgi zone. The characteristic granules of supportive cells are an important feature in the demonstration of small supportive cell segments. The chemical basis of the Friend reaction is not completely understood. However, the reaction proves to be useful in the demonstration of certain cell organelles. A more precise picture of degenerating outer segments of pineal sensory cells and of the distribution of terminal processes of different pineal cell types in the perivascular spaces can be obtained by the prolonged osmium tetroxide fixation. The nerve cells of the anuran pineal organ and their axons are demonstrated selectively by the acetylcholinesterase technique. The basal feet-like processes of the receptor cells and the plexiform zones of the pineal organ are negative in acetylcholinesterase preparations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01033378
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  • 6
    Electronic Resource
    Electronic Resource
    Vergleichende Untersuchungen über acetylcholinesterase-haltige Neurone im Pinealorgan der Vögel (1972)
    Springer
    Cell & tissue research 129 (1972), S. 140-160 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ ; Aves ; Neurons ; Acetylcholinesterase-reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Im Pinealorgan der Vögel zeigen die acetylcholinesterase-positiven Strukturen speziesabhängige Unterschiede. Die passeriformen Arten Passer domesticus, Serinus canaria und Amadina faciata alexander besitzen acetylcholinesterase-positive Nervenzellen, deren Axone im Epiphysenstiel hirnwärts ziehen; außerdem kommen an den Blutgefäßen spezifisch tingierbare Nervenfasern vor, die offenbar zur Epiphyse verlaufen. Bei Columba livia sind diese Nervenstrukturen sehr stark reduziert. Dagegen zeigt das Parenchym der Taubenepiphyse lichtmikroskopisch eine schwache Anfärbung; diese Stellen manifestieren sich im elektronenmikroskopischen Bild als punktförmige interzelluläre Reaktionsorte zwischen einzelnen Pinealzellen. Ferner finden sich bei Passer domesticus elektronenmikroskopisch nachweisbare Reaktionsprodukte im endoplasmatischen Reticulum und im perinukleären Raum der Pinealocyten (=Pinealzellen) sowie am Plasmalemmüberzug (Außenmembran) der Perikaryen und der Axone der Nervenzellen. Die Befunde bei 3 Tage alten Küken (Gallus domesticus) und bei Excalfactoria chinensis ähneln denen bei Columba livia, während bei Coturnix coturnix japonica das Reaktionsprodukt vermehrt im basalen Abschnitt der Follikel liegt. Melopsittacus undulatus zeigt im Epiphysenstiel eine begrenzte Zahl von hirnwärts ziehenden Nervenfasern und nimmt zwischen den Passeriformes und der Taube etwa eine Mittelstellung ein. Die sensorische und sekretorische Kapazität des Pinealorgans von Passeriformes wird diskutiert.
    Notes: Summary The acetylcholinesterase reaction of the pineal organ (epiphysis cerebri) varies among avian species. Acetylcholinesterase-positive neurons with axons running along the pineal stalk to unidentified brain centers are seen in the pineal organ of passeriform birds such as Passer domesticus, Serinus canaria, and Amadina faciata alexander. A different kind of acetylcholinesterase-positive fibers are observed running along the blood vessels to the pineal organ. The acetylcholinesterase-positive structures are much reduced in Columba livia. The pineal parenchyma in Columba livia shows a slightly brown color in the light microscope; spot-like deposits of the reaction product are seen between the pinealocytes in the electron microscope. In Passer domesticus, the reaction products are seen in the pinealocyte endoplasmic reticulum as well as at the outer membrane of the perikaryon and axon of the nerve cells. The results in three-day old chicken and in Excalfactoria chinensis are similar to those obtained in Columba livia. In Coturnix coturnix japonica, a heavy reaction is evident in the basal part of the follicles. A small number of nerve cells and fibers are seen in the pineal stalk of Melopsittacus undulatus. The results are discussed in respect of sensory and secretory functions of the pineal organs in passeriform birds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307115
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  • 7
    Electronic Resource
    Electronic Resource
    Weitere experimentelle und neuroanatomische Untersuchungen an den Nervenbahnen des Pinealkomplexes der Anuren (1971)
    Springer
    Cell & tissue research 116 (1971), S. 250-274 
    Details
    ISSN: 1432-0878
    Keywords: Pineal complex ; Anura ; Nervus and tractus pinealis ; Chromatic and achromatic responses to light
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Der Epiphysenkomplex von 32 Fröschen der Arten Rana temporaria, Rana esculenta und Rana catesbeiana wurde zuerst elektrophysiologisch, anschließend neuro-histologisch bzw. elektronenmikroskopisch untersucht. Auf Belichtung des Stirnorgans lassen sich vom Nervus pinealis (= Tractus frontalis) zwei Arten von Antworten ableiten. Antidrome elektrische Reizung des Tractus pinealis zeigt im Nervus pinealis fortgeleitete Aktionspotentiale und damit Nervenfasern, die vom Stirnorgan bis zum Mittelhirn durchgehen. Elektrophysiologisch wurden außerdem Fasern ermittelt, die die Epiphysis cerebri nicht erreichen. Weitere Fasern enden in der Epiphyse. Neben den vom Stirnorgan zum Gehirn ziehenden afferenten Fasern kann man im extracranialen Teil des Nervus pinealis auch efferente Fasern nachweisen. Histologisch ist in allen Fällen der Durchtritt des Nervus pinealis durch das Schädeldach zu beobachten. Der Durchmesser des Nerven nimmt jedoch wahrend seines Verlaufs kontinuierlich ab. Elektronenmikroskopisch konnte gesichert werden, daß diese Durchmesserabnahme auf einem Faserverlust beruht. Bei einer Rana catesbeiana wurden kurz vor Eintritt des Nervus pinealis in die Epiphyse — im Vergleich zum extracranialen Nervenabschnitt —nur noch die Hälfte der markhaltigen und 1/3 der marklosen Nervenfasern gezählt. Bei den verbleibenden markhaltigen Fasern war außerdem die Dicke der Markscheide stark reduziert. Der Nervus pinealis fächert sich in Epiphysennähe auf; seine Fasern treten dorsomedian einzeln durch die Basalmembran in das Parenchym des rostralen Epiphysenabschnittes ein. Gemeinsam mit den Neuriten der Epiphysennervenzellen bilden sie den Tractus pinealis (s. auch Paul u. Mitarb., 1971). Eine synaptische Umschaltung der Fasern des Nervus pinealis konnte in der Epiphyse nicht nachgewiesen werden. Bei einer Rana esculenta betrug der Faseranteil des Nervus pinealis am Tractus pinealis nur etwa 2%. Die Befunde werden im Zusammenhang mit der Entstehung und Leitung der chromatischen und achromatischen Antwort im Epiphysenkomplex diskutiert.
    Notes: Summary The pineal systems of 32 frogs of the species Rana temporaria, Rana esculenta, and Rana catesbeiana were studied first electrophysiologically and then with histological and electron microscopical methods. The nervus pinealis (= tractus frontalis) showed two kinds of responses to photic stimulation. Uninterrupted conduction of nerve impulses from the frontal organ to the midbrain was demonstrated by antidromic electrical stimulation of the intracranial pineal tract and recording of action potentials from the extracranial pineal nerve. Beside the uninterrupted fibres from the frontal organ to the tractus pinealis, other fibres of the nervus pinealis either did not reach the pineal organ or ended in the pineal organ. The extracranial part of the nervus pinealis contained afferent as well as efferent fibres. Morphologically it was shown in 32 investigated animals that the nervus pinealis penetrates the skull and runs to the pineal organ. During its course, the diameter of the pineal nerve became smaller, which was related to a decrease of the number of myelinated and unmyelinated fibres as revealed by the electron microscope. In comparison with the extracranial portion of the pineal nerve, the intracranial portion of the nerve near the pineal organ contained only half of the myelinated and one third of the unmyelinated fibres counted in one specimen of Rana catesbeiana. The thickness of the myelin sheats of the residual myelinated fibres was much reduced. The nervus pinealis entered the rostral region of the pineal organ, and single nerve fibres were seen to penetrate the basal lamina of the pineal organ reaching its parenchyma dorsomedially. These fibres, and axons of the nerve cells of the pineal organ, constituted the pineal tract (see also Paul et al., 1971). In one specimen of Rana esculenta, only ∼2% of the nerve fibres of the tractus pinealis originated in the frontal organ. The results have been discussed in relation to the generation and conduction of the chromatic and achromatic responses in the pineal system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331265
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  • 8
    Electronic Resource
    Electronic Resource
    Ultracytochemical study of Ca++-ATPase and K+-NPPase activities in retinal photoreceptors of the guinea pig (1984)
    Springer
    Cell & tissue research 237 (1984), S. 479-489 
    Details
    ISSN: 1432-0878
    Keywords: Ca++-ATPase ; K+-NPPase ; Na+-K+ATPase ; Ultracytochemistry ; Photoreceptor cells, retinal ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ca++-ATPase activity was demonstrated histochemically at light- and electron-microscopic levels in inner and outer segments of retinal photoreceptor cells of the guinea pig with the use of a newly developed one-step lead-citrate method (Ando et al. 1981). The localization of ouabain-sensitive, K+-dependent p-nitrophenylphosphatase (K+-NPPase) activity, which represents the second dephosphorylative step of the Na+-K+-ATPase system, was studied by use of the one-step method newly adapted for ultracytochemistry (Mayahara et al. 1980). In retinal photoreceptor cells fixed for 15 min in 2% paraformaldehyde the electron-dense Ca++-ATPase reaction product accumulated significantly on the inner membranes of the mitochondria but not on the plasmalemma or other cytoplasmic elements of the inner segments. The membranes of the outer segments remained unstained except the membrane arrays in close apposition to the retinal pigment epithelium. The cytochemical reaction was Ca++- and substrate-dependent and showed sensitivity to oligomycin. When Mg++-ions were used instead of Ca++-ions, a distinct reaction was also found on mitochondrial inner membranes. In contrast to the localization of the Ca++ -ATPase activity, the K+-NPPase activity was demonstrated only on the plasmalemma of the inner segments, but not on the mitochondria, other cytoplasmic elements or the outer segment membranes. This reaction was almost completely abolished by ouabain or by elimination of K+ from the incubation medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228432
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  • 9
    Electronic Resource
    Electronic Resource
    Ultracytochemical localization of Ca++-ATPase activity in pituicytes of the neurohypophysis of the guinea pig (1984)
    Springer
    Cell & tissue research 237 (1984), S. 491-497 
    Details
    ISSN: 1432-0878
    Keywords: CA++-ATPase ; Pituitary gland, pars nervosa ; Pituicytes ; Neurosecretion ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ca++-ATPase activity (cf. Ando et al. 1981) was examined both light- and electron-microscopically in the neurohypophysis of the guinea pig. Apart from a strong activity within the walls of the blood vessels, in the parenchyma of the neurohypophysis the reaction product of the Ca++-ATPase activity was restricted to the plasmalemma of the pituicytes. This reaction was completely dependent upon Ca++ and the substrate, ATP; the reaction was inhibited by 0.1 mM quercetin, an inhibitor of Ca++-ATPase. A reduction of the enzyme activity occurred by 1) adding Mg++ to the standard incubation medium, and 2) substituting Ca++ with Mg++ at varing concentrations. In all experiments the neurosecretory fibers were devoid of Ca++-ATPase activity. The function of the Ca++-ATPase activity in the plasmalemma of the pituicytes is discussed in connection with the regulation of the extracellular Ca++ concentration, which seems to be important with respect to the discharge of secretory material from the neurosecretory fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228433
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastrukturbesonderheiten der pinealen Sinneszellen von Protopterus dolloi (1969)
    Springer
    Cell & tissue research 100 (1969), S. 560-580 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Pinealorgan (Epiphysis cerebri) von Protopterus dolloi (Dipnoi) enthält Sinneszellaußenglieder, die in Größe und Form denen der Amphibien gleichen. Bemerkenswert sind stark ausgebildete Cilienwurzeln im Innenglied und das Vorhandensein von endoplasmatischem Reticulum und Mikrotubuli im Außenglied. Die Mikrotubuli mit einem Durchmesser von 200 Å strahlen vom Basalteil der Zelle über das Verbindungsstück in das Außenglied ein; es wurde beobachtet, daß sie zwischen den Außengliedlamellen ausmünden. Die Außengliedlamellen zeigen lokale Verbreiterungen bis zu einer Höhe von 700 Å; intrasacculär läßt sich Grundcytoplasma darstellen. Die distalen Außengliedlamellen sind länger als die proximalen und weisen Degenerationszeichen auf, die sich teils als Erweiterung, teils als Komprimierung der Membranenstapel manifestieren. Im Hinblick auf einige morphologische Eigentümlichkeiten der pinealen Photorezeptoren werden Fragen ihres Vitamin A-Metabolismus diskutiert.
    Notes: Summary The pineal organ (epiphysis cerebri) in Protopterus dolloi (Dipnoi) are characterized by sensory cells that in size and shape resemble pineal photoreceptor cells of amphibians. The sensory cell contain in its inner segment fibrous ciliary rootlets and in its outer segment endoplasmic reticulum and microtubules. The microtubules are of 200 Å diameter and extend from the basal part of the sensory cell through the connecting piece into the outer segment, where they end between lamellae in the intersaccular spaces. The lamellae of the outer segment contain intrasaccular hyaloplasm and are enlarged to a maximum thickness of 700 Å. The more distal lamellae are longer than the more proximal ones and suggest a process of degeneration by enlargement or narrowing of their intermembranous spaces. The special morphological characteristics of the pineal photosensory cells are discussed in relation to the vitamin A-metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344376
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